There is no validated assay to reliably detect the early onset of the Lyme disease infection at the time when antibiotic therapy has the best chance of a cure without sequelae. Diagnosis is often difficult because most symptoms are often nebulous, with the telltale bulls-eye rash only appearing and clearly recognizable in approximately half of cases. The standard types of infectious diagnostic tests - both culture and serology - require >3 weeks for a positive result after the onset of infection with Lyme disease. This introduces a significant delay in treatment. While PCR for B. burgdorferi DNA in the blood has potential for a rapid, accurate result, past tests have not had sufficient sensitivity because f few bacteria and low copy numbers of DNA in the blood. We have developed an approach that enlarges the target, substantially increasing the sensitivity of PCR for B. burgdorferi. Our preliminary data show that we can accomplish this by: 1) obtaining a larger sample of blood than usual (10X increase in sensitivity), 2) selectively multiplying the target by using Borrelia-directed primers prior to PCR (200X increase), and 3) probing for the B. burgdorferi on a multi-loci PCR platform (8X increase). To assure reliability and acceptance of a new test based on this approach, we have formally consulted with the FDA from the beginning, and obtained a pre-IDE approval with guidance as to what we need to do for a final cleared test. In this proposal we will test blood samples (from eventually confirmed Lyme cases) with our PCR-based assay at the time of patient presents to prove that it can detect the B. burgdorferi infection earlier and with greater sensitivity specificity than two- tiered serology taken at the same time. Specificity will be assured by testing endemic area controls without Lyme disease. If successful, as our Preliminary and published data suggest, we will follow with a Phase II proposal that analyzes greater number of Lyme disease and control samples to meet the full number for FDA clearance. Our goal is deliver a functional diagnostic assay for Early Onset Lyme Disease that has superior sensitivity and specificity compared to two-tiered serology. The test will permit immediate diagnosis well before seroconversion or cultures become positive so treatment can be started right away.